It is expected that end-user terminals, such as Internet-enabled refrigerators and television sets, that can be connected to a public network such as the Internet will rapidly become commonplace. Their performance has become increasingly higher because of the technological innovations in hardware and software. For example, video recorders and players containing a hard disk are becoming widespread as end-user terminals used in a data delivery management system delivering video data over the Internet. The storage capacity of the hard disk is on the order of several hundred gigabytes, which can record several hundred hours of video.
However, the improvement in the performance often produces unused capabilities for some end-users. For example, for an end user who needs only several hours of video recording time, the remaining several hundred hours of recording capability of a hard disk in a video recorder/player is an excessive capability which he or she does not use but yet should manage. Therefore, there has been a need for effective use of such unused capabilities.